<!DOCTYPE HTML>
<html>
    <head>
        <meta charset="UTF-8">
        <title>留言板</title>
        <style type="text/css">
        *{margin:0; padding:0;}
        body,input{font-size:14px; line-height:24px; color:#333; font-family:Microsoft yahei, Song, Arial, Helvetica, Tahoma, Geneva;}
        h1{margin-bottom:15px; height:100px; line-height:100px; text-align:center; font-size:24px; color:#fff; background:#0051a1;}
        #content #post,#comment p{zoom:1;}
        #content #post:after,#comment p:after{display:block; height:0; clear:both; visibility:hidden; overflow:hidden; content:'.';}
        .transition{-webkit-transition:all 0.5s linear; -moz-transition:all 0.5s linear; -o-transition:all 0.5s linear; -ms-transition:all 0.5s linear; transition:all 0.5s linear;}
        #content{margin:0 auto; width:960px; overflow:hidden;}
        #content #post{margin-bottom:15px; padding-bottom:15px; border-bottom:1px #d4d4d4 dashed;}
        #content #post textarea{display:block; margin-bottom:10px; padding:5px; width:948px; height:390px; border:1px #d1d1d1 solid; border-radius:5px; resize:none; outline:none;}
        #content #post textarea:hover{border:1px #9bdf70 solid; background:#f0fbeb;}
        #content #post #postBt,#content #post #clearBt{margin-left:5px; padding:3px; float:right;}
        #comment{overflow:hidden;}
        #comment p{margin-bottom:10px; padding:10px; border-radius:5px;}
        #comment p:nth-child(odd){border:1px solid #e3e197; background:#ffd;}
        #comment p:nth-child(even){border:1px solid #adcd3c; background:#f2fddb;}
        #comment p span{display:inline; float:left;}
        #comment p .msg{width:738px;}
        #comment p .datetime{width:200px; color:#999; text-align:right;}
        </style>
        <script type="text/javascript">
        var Storage =
        {
            saveData:function()//保存数据
            {
                var data = document.querySelector("#post textarea");
                if(data.value != "")
                {
                    var time = new Date().getTime() + Math.random() * 5;//getTime是Date对象中的方法，作用是返回 1970年01月01日至今的毫秒数
                    localStorage.setItem(time, data.value + "|" + this.getDateTime());//将毫秒数存入Key值中，可以降低Key值重复率
                    data.value = "";
                    this.writeData();
                }
                else
                {
                    alert("请填写您的留言！");
                }
            },
            writeData:function()//输出数据
            {
                var dataHtml = "", data = "";
                for(var i = localStorage.length-1; i >= 0; i--)//效率更高的循环方法
                {
                    data = localStorage.getItem(localStorage.key(i)).split("|");
                    dataHtml += "<p><span class=\"msg\">" + data[0] + "</span><span class=\"datetime\">" + data[1] + "</span></p>";
                }
                document.getElementById("comment").innerHTML = dataHtml;
            },
            clearData:function()//清空数据
            {
                if(localStorage.length > 0)
                {
                    if(window.confirm("清空后不可恢复，是否确认清空？"))
                    {
                        localStorage.clear();
                        this.writeData();
                    }
                }
                else
                {
                    alert("没有需要清空的数据！");
                }
            },
            getDateTime:function()//获取日期时间，例如 2012-03-08 12:58:58
            {
                var isZero = function(num)//私有方法，自动补零
                {
                    if(num < 10)
                    {
                        num = "0" + num;
                    }
                    return num;
                }
                
                var d = new Date();
                return d.getFullYear() + "-" + isZero(d.getMonth() + 1) + "-" + isZero(d.getDate()) + " " + isZero(d.getHours()) + ":" + isZero(d.getMinutes()) + ":" + isZero(d.getSeconds());
            }            
        }
        
        window.onload = function()
        {
            Storage.writeData();//当打开页面的时候，先将localStorage中的数据输出一边，如果没有数据，则输出空
            document.getElementById("postBt").onclick = function(){Storage.saveData();}//发表评论按钮添加点击事件，作用是将localStorage中的数据输出
            document.getElementById("clearBt").onclick = function(){Storage.clearData();}//清空所有已保存的数据
        }
        </script>
    </head>
    
    <body>
        <h1>买家卖家交流板</h1>
        <div id="content">
            <div id="post">
                <textarea class="transition"></textarea>
                <input id="postBt" type="button" value="发表评论"/>
                <input id="clearBt" type="button" value="清空所有已保存的数据"/>
            </div>
            <div id="comment"></div>
        </div>
    </body>
</html>